The present disclosure relates to a semiconductor structure and a method of forming the same. More particularly, the present disclosure relates to a local interconnect structure having a tungsten region whose topmost surface and upper sidewall portions are protected by a self-aligned tungsten nitride passivation layer. The present disclosure also provides a method of forming such a local interconnect structure.
Integrated circuits (ICs) typically include a plurality of semiconductor devices and overlying metal interconnect wiring. A local interconnect, which is sometimes referred to in the art as a Vo level, is typically present between the semiconductor devices and the overlying metal interconnect wiring. Local interconnects typically include a dielectric oxide having a contact via that is filled with tungsten or another like conductive material. During multiple interconnect pattern formation, the upper surface of the tungsten contact gets damaged and/or contaminated. Such damage and/or contamination to the conductive filled contact is undesirable and thus a scheme is needed to protect the exposed surfaces of the conductive filled contact during multiple interconnect patterning.